盾构管片结构设计算例.doc

A Design of Shield Tunnel Lining Part One: Design Data (1) Function of Tunnel The planned tunnel is to be used as a subway tunnel. (2) Design Conditions Dimensions of Segment Type of segment: RC, Flat type Diameter of segmental lining: D0=9500mm Radius of centroid of segmental lining: Rc=4550mm Width of segment: b=1200mm Thickness of segment: t=400mm Ground Conditions Overburden: H=12.3m Groundwater table: G.L.+0.6m =12.3+0.6=12.9m N Value: N=50 Unit weight of soil: =18kN/m3 Submerged unit weight of soil: =8kN/m3 Angle of internal friction of soil: =30o Cohesion of soil: c=0 kN/m2 Coefficient of reaction: k=50MN/m3 Coefficient of lateral earth pressure: =0.4 Surcharge: P0=39.7kN/m2 Soil condition: Sandy Materials The grade of concrete: C30 Nominal strength: fck=20.1N/mm2 Allowable compressive strength: fc=14.3N/mm2 Allowable tensile strength: ft=1.43N/mm2 Elastic modules: E=3.0×104N/mm2 The type of steel bars: HRB335 Allowable strength: fy= fy’= 300N/mm2 Bolt Yield strength: fBy=240N/mm2 Shear strength: =150N/mm2 Parameters for joint spring: 18070 (if inside part of lining is tensile) 32100 (if outside part of lining is tensile) Design Method How to compute member forces? Force method (Part Two) and Elastic equation method (Part Three) are used respectively to calculate member forces. How to check the safety of lining? Limit state method based on the national code GB50010-2002 is used to check the safety of lining. (3) Geometric Design of Shield Lining The shield lining is fitted with 9 segmental pieces (one Key-type segment, two B-type segments and six other segments) as shown in Figure 1. Central angle of each segment piece is 40 degrees. Figure 1 The cross section of the shield lining Part Two: Computation by Force Method (1) Load Conditions Judgment of Tunnel Type (by Terzaghi’s formula) Figure 2 Judgment of tunnel type So the designed tunnel is a shallow tunnel. Load Types and Partial Factors Table 1 shows the loads should be considered in the